Electrode assembly comprising micro-LED elements and method for manufacturing same

ABSTRACT

The present invention relates to an electrode assembly comprising nano-scale-LED elements and a method for manufacturing the same and, more specifically, to an electrode assembly comprising nano-scale-LED elements and a method for manufacturing the same, in which the number of nano-scale-LED elements included in a unit area of the electrode assembly is increased, the light extraction efficiency of individual nano-scale-LED elements is increased so as to maximize light intensity per unit area, and at the same time, nano-scale-LED elements on a nanoscale are connected to an electrode without a fault such as an electrical short circuit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application under 35 U.S.C. § 371of International Application No. PCT/KR2015/012250, filed Nov. 13, 2015,which claims priority to Korean Patent Application No. 10-2014-0161065,filed Nov. 18, 2014, the contents of which applications are incorporatedinto the present application by reference.

TECHNICAL FIELD

The present disclosure relates to an electrode assembly includingnano-scale-light emitting diode (LED) elements and a method formanufacturing the same, and more particularly, to an electrode assemblyincluding nano-scale-LED elements and a method for manufacturing thesame, which are capable of maximizing light intensity of the electrodeassembly per unit area by increasing the number of nano-scale-LEDelements included in a unit area of the electrode assembly and lightextraction efficiency of each of the nano-scale-LED elements, and, atthe same time, are capable of connecting the nano-scale-LED elementsfabricated at a nanoscale size to an electrode without faults such as anelectrical short circuit and the like.

BACKGROUND ART

In 1992, Nakamura et al. of Nichia Corporation in Japan succeeded infusing a high-quality single crystal GaN nitride semiconductor byapplying a low-temperature GaN compound buffer layer thereto, anddevelopment of a light emitting diode (LED) has been actively performed.An LED is a semiconductor having a structure in which an n-typesemiconductor crystal in which a plurality of carriers are electrons anda p-type semiconductor crystal in which a plurality of carriers areholes have a junction using a characteristic of a compoundsemiconductor, and is a semiconductor element that converts anelectrical signal into light having a desired wavelength band and thenemits the light. With regards to such an LED, a method of manufacturingan LED and an LED manufactured by the same are disclosed in KoreanPatent Application Publication No. 2009-0121743.

Such an LED semiconductor is known as a revolution of light as a greenmaterial since light conversion efficiency of the LED semiconductor ishigh, energy consumption thereof is very low, a lifetime thereof issemi-permanent, and the LED semiconductor is environmentally friendly.Recently, high brightness red, orange, green, blue, and white LEDs havebeen developed owing to the development of compound semiconductortechnology, and the LEDs are currently applied in various fields such astraffic lights, a mobile phone, automobile headlights, an outdoordisplay board, and a liquid crystal display (LCD) back light unit (BLU),and research is now being actively performed domestically and abroad.Specifically, since a GaN-based compound semiconductor having a wideband gap is a material that is used to manufacture an LED semiconductorelement which emits green light, blue light, and ultraviolet light, anda white LED element may be fabricated using a blue LED element, studiesis being performed with respect to the fabrication of a white LEDelement.

Among the studies, research has been actively performed using anano-scale-LED element that is fabricated with a nano- ornano-scale-sized LED, and research for utilizing such a nano-scale-LEDelement as lighting and a display are underway. In such research,attention has been continuously focused on an electrode capable ofapplying power to a nano-scale-LED element, an electrode disposition foran application purpose and reducing a space occupied by the electrode, amethod for mounting a nano-scale-LED on a disposed electrode, and thelike.

Among the above areas of focus, there is still difficulty in the methodfor mounting a nano-scale-LED element on a disposed electrode, in whichit is difficult for the nano-scale-LED element to be disposed andmounted as intended on the disposed electrode according to a limitationin size of the nano-scale-LED element. This is because thenano-scale-LED element is fabricated at a nanoscale or nano-scalescalesize, and thus cannot be disposed and mounted on a target electroderegion with a human hand. In addition, although the nano-scale-LEDelement is mounted on the target electrode region, it is very difficultto adjust the number of nano-scale-LED elements included in a unitelectrode region, a positional relationship between the nano-scale-LEDelement and the electrode, and the like to match intentions, and thenumber of LED elements included in a unit area is limited when thenano-scale-LED element is disposed on a two-dimensional plane such thatit is difficult to obtain excellent light intensity. Further, since allnano-scale-LED elements connected to two different electrodes are notable to emit light without faults such as an electrical short circuitand the like, there is a problem in that target light intensity is moredifficult to obtain.

SUMMARY OF THE INVENTION

To address the above described problem, an objective of the presentdisclosure is to provide an electrode assembly including nano-scalelight emitting diode (LED) elements and a method for manufacturing thesame, which are capable of maximizing light intensity per unit area byincreasing the number of nano-scale-LED elements included in a unit areaof the electrode assembly and light extraction efficiency of each of thenano-scale-LED elements, and, at the same time, are capable ofconnecting the nano-scale-LED elements fabricated in a nanoscale size toan electrode without faults such as an electrical short circuit and thelike.

To address the above described problem, the present disclosure providesan electrode assembly including a base substrate; a first electrodeformed on the base substrate to have a first lateral surface; a secondelectrode formed on the base substrate to have a second lateral surfacethat is disposed to face the first lateral surface of the firstelectrode, and a plurality of nano-scale light emitting diode (LED)elements having one end thereof configured to come into contact with thefirst lateral surface and the other end thereof configured to come intocontact with the second lateral surface, and interposed between thefirst electrode and the second electrode.

In accordance with one preferred embodiment of the present disclosure, aheight of each of the first lateral surface and the second lateralsurface may range from 1.1 to 10 times a diameter of each of theplurality of nano-scale-LED elements.

In accordance with another one preferred embodiment of the presentdisclosure, the plurality of nano-scale-LED elements may form amultilayer based on the base substrate.

In accordance with still another one preferred embodiment of the presentdisclosure, the first lateral surface of the first electrode and thesecond lateral surface of the second electrode may be parallel to eachother.

In accordance with another one preferred embodiment of the presentdisclosure, the plurality of nano-scale-LED elements may be connected tothe first lateral surface and the second lateral surface to beperpendicular thereto in a length direction of each of the plurality ofnano-scale-LED elements.

In accordance with still another one preferred embodiment of the presentdisclosure, each of the plurality of nano-scale-LED elements may includea first conductive semiconductor layer; an active layer formed on thefirst conductive semiconductor layer; a second conductive semiconductorlayer formed on the active layer; and an insulating film configured toentirely cover at least an outer surface of the active layer among outersurfaces of each of the plurality of nano-scale-LED elements.

In accordance with another one preferred embodiment of the presentdisclosure, both ends of each of the plurality of nano-scale-LEDelements may include a convex curved surface.

In accordance with still another one preferred embodiment of the presentdisclosure, a length of each of the plurality of nano-scale-LED elementsmay range from 100 nm to 10 μm.

In accordance with still another one preferred embodiment of the presentdisclosure, each of the first electrode and the second electrode mayinclude a portion in which a width of each of the first electrode andthe second electrode narrows toward an upward direction that isperpendicular to the base substrate.

Also, to address the above described problem, the present disclosureprovides an electrode assembly including a plurality of nano-scale-LEDelements disposed in a separation space between a first electrode and asecond electrode which have lateral surfaces facing each other, andconfigured to enable one end of each of the plurality of nano-scale-LEDelements to come into contact with the lateral surface of the firstelectrode and the other end thereof to come into contact with thelateral surface of the second electrode, wherein 1×10³ to 1×10¹²/mm³ ofthe plurality of nano-scale-LED elements are included in the electrodeassembly.

Also, to address the above described problem, the present disclosureprovides a method for manufacturing an electrode assembly, whichincludes (1) forming a first electrode on a base substrate, forming asecond electrode on the base substrate to be spaced apart from the firstelectrode, and disposing a first lateral surface of the first electrodeto face a second lateral surface of the second electrode; (2)introducing a plurality of nano-scale-LED elements and a solvent to aseparation space between the first electrode and the second electrode;and (3) applying electrical power to the first electrode and the secondelectrode to self-align the plurality of nano-scale-LED elements so thatone end of each of the plurality of nano-scale-LED elements comes intocontact with the first lateral surface of the first electrode and theother end thereof comes into contact with the second lateral surface ofthe second electrode.

In accordance with one preferred embodiment of the present disclosure,each of the first electrode and the second electrode may include aportion in which a width of each of the first electrode and the secondelectrode narrows toward the upward direction that is perpendicular tothe base substrate.

In accordance with another one preferred embodiment of the presentdisclosure, each of the plurality of nano-scale-LED elements may includea first conductive semiconductor layer; an active layer formed on thefirst conductive semiconductor layer; a second conductive semiconductorlayer formed on the active layer; and an insulating film configured toentirely cover at least an outer surface of the active layer among outersurfaces of each of the plurality of nano-scale-LED elements.

In accordance with still another one preferred embodiment of the presentdisclosure, both ends of each of the plurality of nano-scale-LEDelements may include a convex curved surface.

In accordance with another one preferred embodiment of the presentdisclosure, a voltage of the electrical power applied to the firstelectrode and the second electrode for 10 to 120 seconds may be in arange of 10 to 500 Vpp.

Terms used herein will be defined below.

In the description of embodiments of the present disclosure, a“separation space” is a region into which a nano-scale-LED element maybe inserted between two different adjacent electrodes, and is referredto as being a space comparted by lateral surfaces, which face eachother, of two different adjacent electrodes, an imaginary bottom surfaceconnecting bottom surfaces of the two adjacent electrodes, and animaginary top surface covering the lateral surfaces, which face eachother, of the two different adjacent electrodes.

In the description of the embodiments the present disclosure, when eachlayer, region, pattern, or structure is referred to as being “on,”“over,” “above,” “under,” “below,” and “lower than” a substrate, itshould be construed that the adverbs “directly” and “indirectly” areincluded in the terms “on,” “over,” “above,” “under,” “below,” and“lower than.”

In the description of the embodiments the present disclosure, a “firstelectrode” and a “second electrode” may include both an electrode regionon which a nano-scale-LED element may be substantially mounted or anelectrode region that may be further included according to a method fordisposing an electrode on a base substrate.

In the description of embodiments the present disclosure, the term“interposed” refers to a nano-scale-LED element being inserted betweendifferent electrodes to be connected to the different electrodes byenabling one end of the nano-scale-LED element to come into contact withone lateral surface of one electrode and the other end thereof to comeinto contact with another lateral surface of the other electrode in aspace between lateral surfaces, which face each other, of the twodifferent electrodes (for example, a first electrode and a secondelectrode). Also, being “electrically coupled” refers to a state inwhich a nano-scale-LED element is inserted between two differentelectrodes and connected to the two different electrodes, and, at thesame time, when electrical power is applied to an electrode line, thenano-scale-LED element emits light.

In the description of the embodiments the present disclosure, “thesame,” “parallel,” or “perpendicular” is referring not to the limitedphysically accurate “the same,” “parallel,” or “perpendicular,” andincludes the extent of substantially “the same,” “parallel,” or“perpendicular.”

In the description of the embodiments the present disclosure, a“multilayer” refers to a single or a plurality of nano-scale-LEDelements forming a single layer with respect to an upward direction thatis perpendicular to a base substrate, and a shape of the layer beingformed, wherein the layer may be a surface that is parallel to orinclined from the base substrate, but does not refer to a surfaceperpendicular to the base substrate.

The electrode assembly of the present disclosure is configured such thata nano-scale light emitting diode (LED) element is three-dimensionallydisposed in a space between electrodes so that the number ofnano-scale-LED elements included in an electrode line per unit area canbe increased, and, at the same time, light extraction efficiency of eachof the nano-scale-LED elements can be improved, thereby maximizing lightintensity of the electrode assembly per unit area. Also, a spaceoccupied by a single nano-scale-LED element in the electrode assemblycan be minimized so that a space in which other nano-scale-LED elementsare able to be disposed can be relatively increased such that the numberof nano-scale-LED elements included in the electrode assembly can beincreased, and thus light intensity can be more increased. Further, ananoscale nano-scale-LED element is connected to an electrode withoutfaults such as an electrical short circuit and the like so that a defectrate of the electrode assembly can be decreased. Moreover, even though anano-scale-LED element does not have a specific structural shape toprevent faults such as an electrical short circuit and the like, adetect rate of a nano-scale-LED electrode assembly can be minimized.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a typical electrode assembly including anano-scale light emitting diode (LED) element.

FIG. 2 is a perspective view of a typical electrode assembly including anano-scale-LED element.

FIG. 3 is a partial perspective view of an electrode assembly accordingto one preferred embodiment of the present disclosure.

FIG. 4 is a perspective view of electrode lines of a first electrode anda second electrode which are formed on a base substrate according to onepreferred embodiment of the present disclosure.

FIG. 5 is a plan view of electrode lines of a first electrode and asecond electrode which are formed on a base substrate according to onepreferred embodiment of the present disclosure.

FIG. 6 is a perspective view of electrode lines of a first electrode anda second electrode which are formed on a base substrate according to onepreferred embodiment of the present disclosure.

FIG. 7 is a plan view and a front view of an electrode assemblyaccording to one preferred embodiment of the present disclosure.

FIG. 8 is a plan view and a front view of an electrode assemblyaccording to one preferred embodiment of the present disclosure.

FIG. 9 is a plan view and a front view of an electrode assemblyaccording to one preferred embodiment of the present disclosure.

FIG. 10 is a plan view and a cross-sectional view taken along line A-Aof an electrode assembly according to one preferred embodiment of thepresent disclosure.

FIG. 11 is a plan view and a cross-sectional view taken along line B-Bof an electrode assembly according to one preferred embodiment of thepresent disclosure.

FIG. 12 is a plan view and a cross-sectional view taken along line C-Cof an electrode assembly according to one preferred embodiment of thepresent disclosure.

FIG. 13 is a plan view and a cross-sectional view taken along line D-Dof an electrode assembly according to one preferred embodiment of thepresent disclosure.

FIG. 14 is a plan view and a front view of an electrode assemblyaccording to one preferred embodiment of the present disclosure.

FIG. 15 is a perspective view illustrating one embodiment of anano-scale-LED element included in the present disclosure.

FIG. 16 is a schematic view illustrating a manufacturing processaccording to one preferred embodiment of the present disclosure.

FIG. 17 is a perspective view illustrating a manufacturing process ofelectrode lines formed on a base substrate according to one preferredembodiment of the present disclosure.

FIG. 18 is a schematic view of Operation (2) according to one preferredembodiment of the present disclosure.

FIG. 19 is a plan view illustrating a self-alignment of a nano-scale-LEDelement according to one preferred embodiment of the present disclosure.

FIG. 20 is a plan view illustrating a self-alignment of a nano-scale-LEDelement according to one preferred embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, one preferred embodiment of the present disclosure will bedescribed in more detail with reference to the accompanying drawings.

As is described above, since a nano-scale light emitting diode (LED)element is not disposed and mounted on a target electrode region with ahuman hand due to a limitation in size of the nano-scale-LED elementaccording to a related art, there is a problem in that it is verydifficult for the nano-scale-LED element to be disposed and mounted asintended on an electrode. FIG. 1 is a perspective view of a typicalelectrode assembly including a nano-scale-LED element, and illustrates afirst electrode 310 formed over a base substrate 300, a second electrode320 formed on the first electrode 310 to be separated therefrom and inparallel therewith, and a nano-scale-LED element 330 connected betweenthe first electrode 310 and the second electrode 320 in athree-dimensionally upright form. In the case of an electrode assemblyhaving such a structure, there is a problem in that it is difficult foreach of LED elements that are separately fabricated to be erected overone electrode in a three-dimensionally upright form. Also, growing anano-scale-LED element on the first electrode 310 causes a problem inthat a manufacturing process is very complicated, and there is a furtherproblem in that a large area electrode assembly cannot be manufacturedthrough such a manufacturing process.

Meanwhile, even when a nano-scale-LED element is mounted on a targetelectrode region in a two-dimensionally reclined form, it is difficultto adjust the number of nano-scale-LED elements included in a unitelectrode region, a positional relationship between the nano-scale-LEDelement and an electrode, and the like as intended. Since the number ofnano-scale-LED elements, which are mountable on a two-dimensional plane,is limited to a unit area of an electrode line, it is difficult toenable a plurality of nano-scale-LED elements capable of obtainingtarget light intensity to be included in the electrode line having alimited area. A diameter size of each of the nano-scale-LED elements isreduced to address the above described problems, but this causes anotherproblem such as a decrease in light extraction efficiency of each of thenano-scale-LED elements, cost issue in a manufacturing method, and thelike. FIG. 2 is a perspective view of a typical electrode assemblyincluding a nano-scale-LED element. FIG. 2 illustrates first electrodes410, 411, and 412 that are each formed on a base substrate 400, secondelectrodes 430, 431, and 432 that are each formed to be spaced apartfrom the first electrodes on the same plane as the first electrodes, anda nano-scale-LED element 421 connected across upper portions of thefirst electrode 421 and the second electrode 432. In the case of anelectrode assembly having such a structure, a nano-scale-LED element isconnected across upper portions of two different electrodes to betwo-dimensionally disposed, and the number of nano-scale-LED elements,which are mounted on an electrode region, is substantially limited to anupper area of the electrode region so that there is a problem in that itis difficult to obtain target light intensity. Further, since all thenano-scale-LED elements connected to the two different electrodes maynot emit light without faults such as an electrical short circuit andthe like, there is a problem in that it is more difficult to obtain thetarget light intensity.

Therefore, the present disclosure solves the above described problems byproviding an electrode assembly including nano-scale LED elements, whichincludes a base substrate, a first electrode formed on the basesubstrate and having a first lateral surface, a second electrode formedon the base substrate and having a second lateral surface that isdisposed to face the first lateral surface of the first electrode, and aplurality of nano-scale-LED elements disposed so that one end of each ofthe nano-scale-LED elements comes into contact with the first lateralsurface and the other end thereof comes into contact with the secondlateral surface, and interposed between the first electrode and thesecond electrode. Through such a solution, an electrode assemblyincluding nano-scale-LED elements having outstanding quality may beimplemented to maximize light intensity per unit area thereof byincreasing the number of nano-scale-LED elements included in a unit areaof the electrode assembly and light extraction efficiency of each of thenano-scale-LED elements, and, at the same time, to connectnano-scale-LED elements fabricated at a nanoscale size to an electrodewithout faults such as an electrical short circuit and the like.

FIG. 3 is a partial perspective view of an electrode assembly accordingto one preferred embodiment of the present disclosure. FIG. 3illustrates a first electrode 10 formed on a base substrate 1, a secondelectrode 20 formed on the base substrate and disposed to face a firstlateral surface I of the first electrode, and a plurality ofnano-scale-LED elements 30 a, 30 b, and 30 c interposed between thefirst electrode 10 and the second electrode 20, and which each have oneend coming into contact with the first lateral surface I of the firstelectrode 10 and the other end coming into contact with a second lateralsurface II of the second electrode 20.

First, the base substrate 1 that is located below the first electrode 10and the second electrode 20 will be described.

The base substrate 1 serves as a supporter of the electrode assembly. Inthe case in which the base substrate 1 is a typical base substrate atwhich an electrode is formed, the base substrate 1 in the presentdisclosure may be used without limitation. As a non-limiting example,the base substrate may be one among a glass substrate, a quartzsubstrate, a sapphire substrate, a plastic substrate, and a flexiblepolymer film. More preferably, the base substrate may be a transparentsubstrate. An area of the base substrate is not limited, and the area ofthe base substrate may be varied in consideration of an area of thefirst electrode and an area of the second electrode, which are to beformed on the base substrate, a size of a nano-scale-LED elementconnected to the first electrode and the second electrode, and thenumber of nano-scale-LED elements connected thereto. Preferably, athickness of the base substrate may be in a range of 100nano-scalemeters (μm) to 1 millimeter (mm), but the thickness is notlimited thereto.

Next, the first electrode 10 and the second electrode 20, which areformed on the above described base substrate 1, will be described.

Being “on the base substrate” refers to the first electrode 10 and thesecond electrode 20 being directly formed on a surface of the basesubstrate, or the first electrode 10 and/or the second electrode 20being formed over the base substrate to be spaced apart therefrom.

FIG. 4 is a perspective view of electrode lines of a first electrode anda second electrode which are formed on a base substrate according to onepreferred embodiment of the present disclosure. All first electrodes 213and 214 and second electrodes 233 and 234 may be directly formed on asurface of a base substrate 200, and the first electrode 214, whichbranches from the first electrode 213, and the second electrode 234,which branches from the second electrode 233, may be alternatelydisposed to form electrode lines 244 which are spaced apart from eachother on the same plane.

Also, FIG. 5 is a plan view of electrode lines of a first electrode anda second electrode which are formed on a base substrate according to onepreferred embodiment of the present disclosure. All first electrodes 212and 215 and second electrodes 232 and 235 may be directly formed on asurface of a base substrate 201, and the first electrode 215, whichbranches from the first electrode 212, and the second electrode 235,which branches from the second electrode 232, may be vertically disposedto form electrode lines 245 which are spaced apart from each other onthe same plane.

Also, FIG. 6 is a perspective view of electrode lines of a firstelectrode and a second electrode which are formed on a base substrateaccording to one preferred embodiment of the present disclosure. A firstelectrode 211 is directly formed on a surface of a base substrate 202,whereas second electrodes 231 and 216 are formed over the base substrate202 to be spaced apart therefrom, and a first electrode 236, whichbranches from the first electrode 211, is connected thereto through aconnection electrode and is formed over the base substrate 202 to bespaced apart from the first electrode 211, and the first electrode 236branched from the first electrode 211 and the second electrode 216,which branches from the second electrode 231, may be alternatelydisposed on the same plane to form electrode lines 246 which are spacedapart from each other.

When the electrode lines are configured in an alternate disposition or avertical disposition as described above, a drive area of a unitelectrode capable of independently driving nano-scale-LED elements whichare included in the base substrate 200, 201, or 202 having a limitedarea may be increased so that the number of nano-scale-LED elementswhich are mounted on a unit electrode area may be increased through adisposition of electrodes. This may increase light emitting intensityper unit area of the nano-scale-LED element so that the nano-scale-LEDelement may be useful in an application of various opto-electronicdevices which require high brightness per unit area. Meanwhile, FIGS. 4to 6 illustrate one preferred embodiment, and the present disclosure isnot limited thereto and may further be modified and implemented invarious manners according to the purpose of the present disclosurethrough a disposition of all imaginable structures in which twoelectrodes are spaced apart from each other at regular intervals.

Meanwhile, the first electrode 10 and the second electrode 20 may eachbe configured with a material that is generally used as an electrode. Asa non-limiting example, the first electrode 10 and the second electrode20 may each be independently configured with one or more metal materialsselected from a group consisting of aluminum, titanium, indium, gold,and silver, or one or more transparent materials selected from a groupconsisting of indium tin oxide (ITO), ZnO:Al, and a carbon nanotube(CNT)—conductive polymer complex. When two or more kinds of electrodematerials are used, the first electrode 10 and/or the second electrode20 may preferably have a structure in which the two or more kinds ofelectrode materials are stacked. More preferably, the first electrode 10and/or the second electrode 20 may be an electrode in which two kinds ofmaterials, that is, titanium and gold are stacked. However, thematerials of the first electrode 10 and/or the second electrode 20 arenot limited to the above described materials. Also, the materials of thefirst electrode 10 and/or the second electrode 20 may be the same as ordifferent from each other.

In addition, heights of the first electrode 10 and the second electrode20 (each of the heights corresponding to a thickness in an upwarddirection that is perpendicular to the base substrate) may be designedto be different from each other according to a purpose of each of thefirst electrode 10 and the second electrode 20. In accordance with onepreferred embodiment of the present disclosure, a height of each of thefirst lateral surface I of the first electrode 10 and the second lateralsurface II of the second electrode may be formed to be from 1.1 to 10times a diameter of the nano-scale-LED element, more preferably, to befrom 2 to 10 times the diameter of the nano-scale-LED so that thenano-scale-LED element may form a multilayer in a height direction ofeach of two different adjacent electrodes in a separation space betweenthe two different adjacent electrodes. When the height of one of thelateral surfaces of the two different adjacent electrodes is less than1.1 times the diameter of the nano-scale-LED element, the nano-scale-LEDelement may be inserted into the separation space between the twodifferent adjacent electrodes and connected to the two differentadjacent electrodes, but may not form the multilayer since the height ofthe lateral surface is small. Because such a case is the same as thecase in which the nano-scale-LED element is disposed at the electroderegion, that is, in a two-dimensional plane, there is a problem in thata physical property that is the target of the present disclosure may notbe implemented. Also, when the height of one of the lateral surfaces ofthe two different adjacent electrodes exceeds 10 times the diameter ofthe nano-scale-LED element, the number of nano-scale-LED elements whichare inserted into the separation space between the two differentadjacent electrodes and connected to the two different adjacentelectrodes may be uneconomically increased, and, at the same time, itmay be difficult to enable all the nano-scale-LED elements to emit lightdue to a connection problem with the two different adjacent electrodes.Further, even when a nano-scale-LED element located at a lower layeramong a plurality of layers emits light, the light may be blocked by anano-scale-LED element that is disposed over the nano-scale-LED elementlocated at the lower layer so that there may be a problem in that lightextraction efficiency is not significantly increased.

In addition, each of the first lateral surface I of the first electrode10 and the second lateral surface II of the second electrode maypreferably be disposed perpendicular to the base substrate. When thefirst lateral surface I and the second lateral surface II are eachformed to be inclined with respect to the base substrate, a distancebetween the first electrode 10 and the second electrode 20 variesaccording to the height of the first lateral surface I or the secondlateral surface II so that there is a problem in that it may bedifficult to interpose the nano-scale-LED element between the firstelectrode 10 and the second electrode 20 in the form of the multilayerbased on the base substrate. Although the nano-scale-LED element isinterposed between the first electrode 10 and the second electrode 20, afault occurs in a positional relationship between the nano-scale-LEDelements so that there is a problem in that the number of nano-scale-LEDelements that may be included in a unit volume of a separation spacebetween the first electrode 10 and the second electrode 20 may bedecreased.

In addition, the first lateral surface I of the first electrode 10 andthe second lateral surface II of the second electrode may preferably beformed to be perpendicular to the base substrate, and, at the same time,to be parallel to each other. In the case in which the lateral surfacesI and II of the first electrode 10 and the second electrode 20 are notparallel to each other even when disposed perpendicular to the basesubstrate, the distance between the first electrode 10 and the secondelectrode 20 varies in a length direction of each of the first electrode10 and the second electrode 20 (that is, the distance is graduallyincreased or decreased) so that it may be difficult to interpose thenano-scale-LED element therebetween based on the base substrate.Although the nano-scale-LED element is interposed between the firstelectrode 10 and the second electrode 20, a fault occurs in thepositional relationship between the nano-scale-LED elements so thatthere is a problem in that the number of nano-scale-LED elements thatmay be included in a unit volume of the separation space between thefirst electrode 10 and the second electrode 20 may be decreased.

Further, the lateral surfaces I and II facing each other of the firstelectrode 10 and the second electrode 20 may each be provided to be flatso as to enable a surface contact between both ends of thenano-scale-LED element and the lateral surfaces I and II of the firstelectrode 10 and the second electrode 20. When one end of thenano-scale-LED element is connected to the lateral surface I or II ofthe first electrode 10 or the second electrode 20 through the surfacecontact, an electrical connection thereof may be superior when comparedto that of a point or line contact so that there is an advantage in thata fault is prevented from occurring.

Also, a cross-sectional shape of each of the first electrode 10 and thesecond electrode 20 may vary in a vertical direction with respect to thebase substrate, and the cross-sectional shape may include a portion atwhich a width of the first electrode 10 or the second electrode 20narrows toward the upward direction that is perpendicular to the basesubstrate. An outer surface corresponding to the portion at which thewidth narrows in the cross-sectional shape of the first electrode 10 orthe second electrode 20 may not be a portion on which the nano-scale-LEDelement is substantially mounted. When the first electrode 10 or thesecond electrode 20 having such a cross-sectional shape is employed, thenano-scale-LED element may be more easily located in the separationspace between the first electrode 10 and the second electrode 20 duringa manufacturing process of the electrode assembly which will bedescribed below. A detailed description of the above-describednano-scale-LED element will be followed by a description of amanufacturing process which will be described below.

Also, a width of each of the first electrode 10 and the second electrode20 may be in a range of 100 nanometers (nm) to 50 μm, but is not limitedthereto, and the width may be designed to be different according to adetailed disposition of the first electrode 10 and the second electrode20 and an application field thereof. In addition, a thickness of each ofthe first electrode 10 and the second electrode 20 may be in a range of200 nm to 50 μm, but is not limited thereto, and the thickness may bedesigned to be different according to the diameter of the nano-scale-LEDelement.

Meanwhile, a distance between the first lateral surface I of the firstelectrode 10 and the second lateral surface II of the second electrode20 may be designed to be different according to a detailed shape,length, and diameter of the nano-scale-LED element without limitation toa concrete shape, length, and diameter thereof, and preferably, thediameter thereof may be less than or equal to the length of thenano-scale-LED element.

Further, the electrode assembly according to the present disclosure isprovided such that one end of the electrode assembly is disposed to comeinto contact with the first lateral surface of the first electrode thathas been described in detail, and the other end thereof is disposed tocome into contact with the second lateral surface of the secondelectrode that has been described in detail, and the electrode assemblyincludes a plurality of nano-scale-LED elements interposed between thefirst electrode and the second electrode.

In particular, as shown in FIG. 3, the plurality of nano-scale-LEDelements 30 a, 30 b, and 30 c are inserted into the separation spacebetween the first electrode 10 and the second electrode 20 and connectedto the first electrode 10 and the second electrode 20 so that one end ofeach of the plurality of nano-scale-LED elements 30 a, 30 b, and 30 ccomes into contact with the first lateral surface I of the firstelectrode 10 and the other end thereof comes into contact with thesecond lateral surface II of the second electrode 20 adjacent to thefirst electrode 10. The plurality of nano-scale-LED elements 30 a, 30 b,and 30 c are laid in parallel with the base substrate in a lengthdirection of each of the plurality of nano-scale-LED elements 30 a, 30b, and 30 c to be connected to adjacent electrodes, that is, the firstelectrode 10 and the second electrode 20.

First, a positional relationship between the plurality of nano-scale-LEDelements will be described, wherein the plurality of nano-scale-LEDelements are each inserted between the first lateral surface I of thefirst electrode 10 and the second lateral surface II of the secondelectrode 20, which is disposed to face the first lateral surface I ofthe first electrode 10, to be connected to the first electrode 10 andthe second electrode 20.

In accordance with one preferred embodiment of the present disclosure,the plurality of nano-scale-LED elements may be inserted between thefirst electrode and the second electrode and connected to the firstelectrode and the second electrode to form the multilayer based on thebase substrate.

FIG. 7A is a plan view of an electrode assembly according to another onepreferred embodiment of the present disclosure. FIG. 7A illustratesnano-scale-LED elements 31 a and 31 e which are inserted between a firstlateral surface I of a first electrode 11, which is perpendicular to abase substrate (not shown), and a second lateral surface II of a secondelectrode 21, which is disposed to be parallel to and to face the firstlateral surface I, to be connected to the first electrode 11 and thesecond electrode 21. Also, FIG. 7B is a front view with respect to FIG.7A, and illustrates a plurality of nano-scale-LED elements 31 a, 31 b,31 c, 31 d, and 31 e which are inserted into a separation space betweenthe first electrode 11 and the second electrode 21 which are formed on abase substrate 1 to be connected to the first electrode 11 and thesecond electrode 21. At this point, the plurality of nano-scale-LEDelements 31 b, 31 c, 31 d, and 31 e form layers L1, L2, L3 and L4 basedon the base substrate 1. In FIGS. 7A and 7B, a length direction of afirst nano-scale-LED element 31 a is inclined with respect to the basesubstrate 1, and the first nano-scale-LED element 31 a is insertedbetween the first electrode 11 and the second electrode 21 to beinclined thereto instead of being perpendicular to each of the firstelectrode 11 and the second electrode 21, and thus is connected to thefirst electrode 11 and the second electrode 21. As will be described inthe manufacturing process which will be described below, each of thenano-scale-LED elements may not be manually assembled between theelectrodes but may be interposed between the electrodes as the firstnano-scale-LED element 31 a included in the electrode assembly shown inFIGS. 7A and 7B. However, in the separation space between the firstelectrode 11 and the second electrode 21, a region occupied by the firstnano-scale-LED element may be greater than that occupied by each of theremaining nano-scale-LED elements 31 b, 31 c, 31 d, and 31 e so that thenumber of nano-scale-LED elements which may be included in a limitedvolume of the separation space may be reduced. In particular, a lengthx₁ occupied by the first nano-scale-LED element 31 a in FIG. 7A isgreater than a diameter h of the nano-scale-LED element, and a height y₁occupied by the first nano-scale-LED element 31 a in FIG. 7B is alsogreater than the diameter h of the nano-scale-LED element, and thus aseparation space (having the length x₁, a width which is the distancebetween the first electrode 11 and the second electrode 21, and theheight y₁) occupied by the first nano-scale-LED element may besignificantly greater than a separation space S2 (having a length h, awidth which is the distance between the first electrode 11 and thesecond electrode 21, and a height h) occupied by another nano-scale-LEDelement 31 b so that a space in which the other nano-scale-LED elementis interposed may be reduced.

Therefore, in accordance with another one preferred embodiment of thepresent disclosure, the nano-scale-LED elements may be disposed to beparallel to the base substrate or between the nano-scale-LED elements inthe length direction of each of the nano-scale-LED elements to beinterposed in the separation space between the first electrode and thesecond electrode. More preferably, the nano-scale-LED elements may bedisposed to be parallel not only to the base substrate but also betweenthe nano-scale LED elements in the length direction of each of thenano-scale LED elements to be interposed between the first electrode andthe second electrode. FIG. 8A is a plan view of the electrode assemblyaccording to one preferred embodiment of the present disclosure. FIG. 8Aillustrates nano-scale-LED elements 32 a and 32 b which each areinserted between a first lateral surface of a first electrode 12, whichis perpendicular to a base substrate (not shown), and a second lateralsurface of a second electrode 22, which is disposed to be parallelthereto and to face the first lateral surface, to be connected to thefirst electrode 11 and the second electrode 21. At this point, somenano-scale-LED elements 32 a ₁ and 32 a ₂ are disposed in parallel witheach other in a length direction and interposed between the first andsecond electrodes, and other nano-scale-LED elements 32 b ₁ and 32 b ₂are also disposed in parallel with each other in the length directionand interposed between the first and second electrodes. Also, FIG. 8B isa front view with respect to FIG. 8A and illustrates the plurality ofnano-scale-LED elements 32 a and 32 b which are inserted into aseparation space between the first electrode 12 and the second electrode22 which are formed on a base substrate 1 to be connected to the firstelectrode 12 and the second electrode 22. At this point, the pluralityof nano-scale-LED elements 32 a and 32 b_form a two-stage multilayerthat is parallel to the base substrate 1. As shown in FIG. 8B, when thetwo-stage multilayer that is parallel to the base substrate 1 is formed,a height which is occupied by each of the plurality of nano-scale-LEDelements 32 a and 32 b in the separation space corresponds to a diametery₂ of each of the plurality of nano-scale-LED elements 32 a and 32 bsuch that there may be an advantage in that the number of layers thatmay be included in an electrode having a limited height may besignificantly increased. Meanwhile, in the electrode assembly shown inFIG. 8A, the plurality of nano-scale-LED elements are disposed inparallel with each other in the length direction of each of theplurality of nano-scale-LED elements and are interposed between theelectrodes so that a volume of the separation space occupied by theplurality of nano-scale-LED elements may be reduced in comparison tothat of when the plurality of nano-scale-LED elements are irregularlyinterposed between the electrodes instead of being interposed inparallel with each other in the length direction. On the other hand, thevolume of the separation space may be increased in comparison to that ofwhen the plurality of nano-scale-LED elements are not only disposed inparallel with each other in the length direction but are also connectedperpendicular to both the first electrode and the second electrode suchthat there is a problem in that the number of nano-scale-LED elementsthat may be included in the separation space may be reduced.

Accordingly, in accordance with one preferred embodiment of the presentdisclosure, the plurality of nano-scale-LED elements may be connected tobe perpendicular to the lateral surface of each of the electrodes in thelength direction of each of the plurality of nano-scale-LED elements.FIG. 9 is a plan view and a front view of an electrode assemblyaccording to still another one preferred embodiment of the presentdisclosure. FIG. 9 illustrates nano-scale-LED elements 33 a ₁ and 33 a ₂which are inserted between a first lateral surface of a first electrode13, which is perpendicular to a base substrate (not shown), and a secondlateral surface of a second electrode 23, which is disposed to beparallel to and to face the first lateral surface, to be connected tothe first electrode 13 and the second electrode 23. At this point, thenano-scale-LED elements 33 a ₁ and 33 a ₂ are disposed in parallel witheach other in a length direction and are interposed between both thefirst electrode 13 and the second electrode 23 to be perpendicularthereto in the length direction. Also, FIG. 9B illustrates the pluralityof nano-scale-LED elements 33 a and 33 b which are inserted into aseparation space between the first electrode 13 and the second electrode23 which are formed on a base substrate 1 to be connected to the firstelectrode 13 and the second electrode 23. At this point, nano-scale-LEDelements 33 a (that is, 33 a ₁ and 33 a ₂) form a first layer that isparallel to the base substrate 1 and nano-scale-LED elements 33 b form asecond layer that is parallel to the base substrate 1 and is spacedapart from the first layer so that the plurality of nano-scale-LEDelements included in the electrode assembly of FIG. 9B form a four-stagemultilayer.

Meanwhile, FIG. 10 is a plan view and a cross-sectional view taken alongline A-A of the electrode assembly according to still another onepreferred embodiment of the present disclosure. FIG. 10A illustratesnano-scale-LED elements 34 a ₁, 34 a ₂, 34 a ₃, 34 b ₁, and 34 b ₂ whichare inserted between a first lateral surface of a first electrode 14,which is perpendicular to a base substrate (not shown), and a secondlateral surface of a second electrode 24, which is disposed to beparallel to and to face the first lateral surface, to be connected tothe first electrode 14 and the second electrode 24. At this point 1, thenano-scale-LED elements 34 a ₁, 34 a ₂, 34 a ₃, 34 b ₁, and 34 b ₂ aredisposed in parallel with each other in a length direction and areinterposed between both the first electrode 14 and the second electrode24 to be perpendicular thereto in the length direction. Also, FIG. 10Bis the cross-sectional view taken along line A-A of FIG. 10A andillustrates a cross section of each of the nano-scale-LED elements 34 a₁, 34 a ₂, 34 a ₃, 34 b ₁, and 34 b ₂ which has one end coming intocontact with the first electrode 14 formed on a base substrate 1. InFIG. 10B, the nano-scale-LED elements 34 a ₁, 34 a ₂, and 34 a ₃ form afirst layer that is parallel to the base substrate 1, and thenano-scale-LED elements 34 b ₁ and 34 b ₂ form a second layer that isparallel to the base substrate 1 and is spaced apart from the firstlayer, and FIG. 10B illustrates a three-stage multilayer. At this point,a second nano-scale-LED element 34 b ₁ included in the second layer islocated below a separation space between a third nano-scale-LED element34 a ₁ and a fourth nano-scale-LED element 34 a ₂ which are included inthe first layer, instead of being located vertically below the thirdnano-scale-LED element 34 a ₁ included in the first layer. With such aconfiguration, it is possible to minimize blockage of light emitted fromthe second nano-scale-LED element 34 b ₁ included in the second layer bythe third nano-scale-LED element 34 a ₁ included in the first layer suchthat the light does not propagate toward a front portion that isperpendicular to the base substrate.

Also, FIG. 11 is a plan view and a cross-sectional view taken along lineB-B of an electrode assembly according to one preferred embodiment ofthe present disclosure. FIG. 11A illustrates nano-scale-LED elements 35a ₁, 35 a ₂, 35 a ₃, and 35 b ₁ which are inserted between a firstlateral surface of a first electrode 15, which is perpendicular to abase substrate (not shown), and a second lateral surface of a secondelectrode 25, which is disposed to be parallel to and to face the firstlateral surface, to be connected to the first electrode 15 and thesecond electrode 25. At this point, the nano-scale-LED elements 35 a ₁,35 a ₂, 35 a ₃, and 35 b ₁ are disposed in parallel with each other in alength direction and are interposed between both the first electrode 15and the second electrode 25 to be perpendicular thereto in the lengthdirection.

At this point, in FIGS. 11A and 11B, outer surfaces of the fifthnano-scale-LED element 35 a ₁ and the sixth nano-scale-LED element 35 a₂ come into line contact with each other in the length direction. Atypical nano-scale-LED element includes an active layer in which anelectron-hole pair is formed to generate light, and the active layer isgenerally formed not only at a central position of the typicalnano-scale-LED element but also at a position biased toward one end ofthe typical nano-scale-LED element. Positions of active layers innano-scale-LED elements which are grown and manufactured may bedifferent from each other, and in the case of the typical LED element,the active layer is exposed to an outer surface of the typical LEDelement. When the active layer comes into contact with an electrode ofan electrode line to which electrical power is directly applied or witha semiconductor layer of a nano-scale-LED element to which electricalpower is applied, an electrical short circuit may occur at such anano-scale-LED element and the nano-scale-LED element may not emitlight.

In particular, as shown in FIG. 11A, an active layer (P in FIG. 11A) ofthe fifth nano-scale-LED element 35 a ₁ comes into contact with aconductive semiconductor layer (or an electrode layer that may be formedbelow the conductive semiconductor layer) of the sixth nano-scale-LEDelement 35 a ₂, and, at the same time, an active layer (Q in FIG. 11A)of the sixth nano-scale-LED element 35 a ₂ comes into contact with aconductive semiconductor layer (or an electrode layer that may be formedbelow the conductive semiconductor layer) of the fifth nano-scale-LEDelement 35 a ₁. When electrical power is applied to the first electrode15 and the second electrode 25, an electrical short circuit may occureven though the fifth nano-scale-LED element 35 a ₁ and the sixthnano-scale-LED element 35 a ₂ are disposed between the first electrode15 and the second electrode 25 and the fifth nano-scale-LED element 35 a₁ and the sixth nano-scale-LED element 35 a ₂ may not emit light. Whensuch a fault frequently occurs, even though the number of nano-scale-LEDelements that are included in a separation space between the twodifferent electrodes is significantly increased, an electrode assemblycapable of obtaining target light intensity may not be implemented.

To address the above described problem and to interpose morenano-scale-LED elements in a separation space which is limited in size,in accordance with one preferred embodiment of the present disclosure, anano-scale-LED element may include a first conductive semiconductorlayer, an active layer formed on the first conductive semiconductorlayer, a second conductive semiconductor layer formed on the activelayer, and an insulating film configured to entirely cover at least anouter surface of the active layer of an entire outer surface of thenano-scale-LED element.

FIG. 15 is a perspective view illustrating one embodiment of anano-scale-LED element included in the present disclosure, andillustrates an active layer 30B formed on a first conductivesemiconductor layer 30A, a second conductive semiconductor layer 30Cformed on the active layer 30B, and an insulating film 30F configured tocover outer surfaces of the first conductive semiconductor layer 30A,the active layer 30B, and the second conductive semiconductor layer 30C.

Since the insulating film 30F covers the outer surface of the activelayer 30B, even though electricity is directly applied to the outersurface of the active layer 30B of the nano-scale-LED element, theactive layer 30B may be protected by the insulating film 30F so that anelectrical short circuit of the nano-scale-LED element may be prevented.Accordingly, an outer surface of the nano-scale-LED element included inone preferred embodiment of the present disclosure may include theinsulating film 30F configured to entirely cover at least the outersurface of the active layer. When the insulating film is coated on theouter surface of the nano-scale-LED element that includes the activelayers of the fifth nano-scale-LED element 35 a ₁ and the sixthnano-scale-LED element 35 a ₂ in FIG. 11A, an electrical short circuitmay not occur when electrical power is applied thereto even though thefifth nano-scale-LED element 35 a ₁ and the sixth nano-scale-LED element35 a ₂ are interposed between the first electrode 15 and the secondelectrode 25 to enable the outer surfaces of the two nano-scale-LEDelements to come into line contact with each other. In addition, theinsulating film 30F may preferably be coated even on one or more of theouter surfaces of the first conductive semiconductor layer 30A and thesecond conductive semiconductor layer 30C to simultaneously prevent anelectrical short circuit and a degradation of durability of thenano-scale-LED element due to damage to the outer surfaces of thesemiconductor layers.

Therefore, an electrode assembly according to another one preferredembodiment of the present disclosure may be configured such thatnano-scale-LED elements may be interposed in a separation space betweentwo different adjacent electrodes by maximally packing outer surfaces ofthe nano-scale-LED elements to come into contact with each othervertically and horizontally with respect to a base substrate. With sucha configuration, the number of nano-scale-LED elements included in theseparation space per unit volume may be significantly increased, and, atthe same time, an electrical short circuit of the nano-scale-LED elementmay not occur so that outstanding light intensity is obtained. FIG. 12is a plan view and a cross-sectional view taken along line C-C of anelectrode assembly according to another one preferred embodiment of thepresent disclosure. FIG. 12A illustrates nano-scale-LED elements 36 a ₁,36 a ₂, 36 a ₃, and 36 a ₄ which are inserted between a first lateralsurface of a first electrode 16, which is perpendicular to a basesubstrate (not shown), and a second lateral surface of a secondelectrode 26, which is disposed to be parallel to and to face the firstlateral surface, to be connected to the first electrode 16 and thesecond electrode 26. At this point, the nano-scale-LED elements 36 a ₁,36 a ₂, 36 a ₃, and 36 a ₄ are disposed in parallel with each other in alength direction and are interposed between both the first electrode 16and the second electrode 26 to be perpendicular thereto in the lengthdirection, and, at the same time, outer surfaces of the nano-scale-LEDelements come into contact with each other. Also, FIG. 12B is thecross-sectional view taken along line C-C of FIG. 12A and illustrates across section of each of the nano-scale-LED elements 36 a ₁, 36 b, 36 c,and 36 d that has one end coming into contact with the first electrode16 formed on a base substrate 1. In FIG. 12B, the nano-scale-LED element36 a ₁ forms a first layer that is parallel to the base substrate 1, andthe nano-scale-LED element 36 b forms a second layer that is parallel tothe base substrate 1 and comes into contact with the first layer, thenano-scale-LED element 36 c forms a third layer that is parallel to thebase substrate 1 and comes into contact with the second layer, and FIG.12B illustrates a multilayer in which four stage layers each come intocontact with layers adjacent thereto. As shown in FIG. 12B, when theplurality of nano-scale-LED elements are packed in a separation spacebetween the two adjacent electrodes 16 and 26, the number ofnano-scale-LED elements included in the separation space that is limitedin size may be significantly increased, and an insulating film may befurther coated on an outer surface corresponding to an active layer ofeach of the plurality of nano-scale-LED elements to prevent anelectrical short circuit so that an electrode assembly capable ofobtaining target light intensity may be implemented without faults.

Meanwhile, in accordance with one preferred embodiment of the presentdisclosure, nano-scale-LED elements interposed in a separation spacebetween two different adjacent electrodes may randomly form a multilayerbased on a base substrate. FIG. 13 is a plan view and a cross-sectionalview taken along line D-D of an electrode assembly according to onepreferred embodiment of the present disclosure. As can be seen fromFIGS. 13A and 13B, nano-scale-LED elements 37 a, 37 b, and 37 c mayrandomly form a multilayer in a separation space between a firstelectrode 17 and a second electrode 27, some of the nano-scale-LEDelements may be spaced apart from each other without contact betweenouter surfaces of some of the nano-scale-LED elements, and the remainingnano-scale-LED elements may be interposed between the electrodes toenable outer surfaces of the remaining nano-scale-LED elements to comeinto contact with each other.

In accordance with still another one preferred embodiment of the presentdisclosure, both ends of a nano-scale-LED element included in anelectrode assembly may each include a convex curved surface.

FIG. 14 is a plan view and a front view of an electrode assemblyaccording to still another one preferred embodiment of the presentdisclosure. Each of both ends of nano-scale-LED elements 38 a ₁ and 38 a₂, which are inserted into a separation space between a first electrode18 and a second electrode 28 which are formed on a base substrate 1 tobe connected to the first electrode 18 and the second electrode 28,includes a convex curved surface. When each of both of the ends of anano-scale-LED element includes the convex curved surface, in a processof self-aligning the nano-scale-LED element during a manufacturingprocess of an electrode assembly which will be described below, there isan advantage in that the nano-scale-LED element may be inserted into twodifferent electrodes to more easily enable lateral surfaces of the twodifferent electrodes to be approximately perpendicular to a lengthdirection of the nano-scale-LED element and may be connected to the twodifferent electrodes, and a detailed description thereof will bedescribed in the manufacturing process which will be described below.

Meanwhile, another one embodiment of the present disclosure includes aplurality of nano-scale-LED elements disposed in a separation spacebetween first and second electrodes with lateral surfaces facing eachother so that one end of each of the plurality of nano-scale-LEDelements may come into contact with the lateral surface of the firstelectrode and the other end thereof may come into contact with thelateral surface of the second electrode, and 1×10³ to 1×10¹²/mm³ of theplurality of nano-scale-LED elements are included an electrode assembly.

The electrode assembly is configured such that the plurality ofnano-scale-LED elements are disposed to form a multilayer in theseparation space between the first and second electrodes with thelateral surfaces facing each other so that 1×10³ to 1×10¹²/mm³ of theplurality of nano-scale-LED elements are interposed in the separationspace, which is significantly increased in comparison to that of whenthe plurality of nano-scale-LED elements are simply mounted on a singleplane. With such a configuration, the number of nano-scale-LED elementsincluded in the electrode assembly per unit area may be significantlyincreased when compared to that of a typical electrode assembly so thatoutstanding light intensity may be obtained.

Next, a nano-scale-LED element included in an electrode assemblyaccording to the present disclosure will be described in more detail.

A nano-scale-LED element that may be used in the present disclosure mayemploy any nano-scale-LED element generally used in lighting or adisplay without limitation. Preferably, a length of the nano-scale-LEDelement may be in a range of 100 nm to 10 μm, and more preferably, in arange of 500 nm to 5 μm. When the length of the nano-scale-LED elementis less than 100 nm, it may be difficult to manufacture a highefficiency nano-scale-LED element, whereas when the length of thenano-scale-LED element exceeds 10 μm, light emitting efficiency of thenano-scale-LED element may be degraded. A shape of the nano-scale-LEDelement may be various shapes such as a cylindrical shape, a rectangularparallelepiped shape, and the like, and preferably, the shape may be acylindrical shape, but is not limited to the above-described shapes.

In the following description of the nano-scale-LED element, “on,”“under,” “upward,” “downward,” “over,” and “below” refer to verticallyupward and downward directions based on each layer included in thenano-scale-LED element.

The nano-scale-LED element may include a first conductive semiconductorlayer, an active layer formed on the first conductive semiconductorlayer, and a second conductive semiconductor layer formed on the activelayer. FIG. 15 illustrates the active layer 30B formed on the firstconductive semiconductor layer 30A, and the second conductivesemiconductor layer 30C formed on the active layer 30B.

First, the first conductive semiconductor layer 30A will be described.The first conductive semiconductor layer 30A may include, for example,an n-type semiconductor layer. When the nano-scale-LED element is a bluelight emitting element, the n-type semiconductor layer may be configuredwith a semiconductor material having a composition formula ofInxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, and 0≤x+y≤1), for example, one or morematerials that may be selected from InAlGaN, GaN, AlGaN, InGaN, AlN,InN, and the like, and a first conductive dopant (for example, Si, Ge,Sn, and the like) may be doped on the n-type semiconductor layer.Preferably, a thickness of the first conductive semiconductor layer 30Amay be in a range of 500 nm to 5 μm, but the thickness is not limitedthereto. Since light emission of the nano-scale-LED element is notlimited to the blue color, when a color of the light emission is varied,a different kind of III-V semiconductor material may be used as then-type semiconductor layer without limitation.

Next, the active layer 30B formed on the first conductive semiconductorlayer 30A will be described. When the nano-scale-LED element is a bluelight emitting element, the active layer 30B may be formed on the firstconductive semiconductor layer 30A and with a single or multiple quantumwell structure. A clad layer (not shown) doped with a conductive dopantmay be formed on and/or under the active layer 30B, and may beimplemented with an AlGaN layer or an InAlGaN layer. In addition,materials such as AlGaN, AlInGaN, and the like may be used as the activelayer 30B. When an electric field is applied to such an active layer30B, light is generated in the active layer 30B due to electron-holepairs recombination. Preferably, a thickness of the active layer 30B maybe in a range of 10 nm to 200 nm, but the thickness is not limitedthereto. The active layer 30B may be formed at various positionsaccording to a kind of nano-scale-LED element. Since light emission ofthe nano-scale-LED element is not limited to the blue color, when acolor of the light emission is varied, a different kind of III-Vsemiconductor material may be used as the active layer withoutlimitation.

Next, the second conductive semiconductor layer 30C formed on the activelayer 30B will be described. When the nano-scale-LED element is a bluelight emitting element, the second conductive semiconductor layer 30Cmay be formed on the active layer 30B and may be implemented with atleast one p-type semiconductor layer. The p-type semiconductor layer maybe configured with a semiconductor material having a composition formulaof InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, and 0≤x+y≤1), for example, one or morematerials that may be selected from InAlGaN, GaN, AlGaN, InGaN, AlN,InN, and the like, and a second conductive dopant (for example, Mg) maybe doped on the p-type semiconductor layer. Here, a light emittingstructure includes the first conductive semiconductor layer 30A, theactive layer 30B, and the second conductive semiconductor layer 30C asminimum components thereof, and the light emitting structure may furtherinclude a different phosphor layer, a different active layer, adifferent semiconductor layer, and/or a different electrode layeron/under each of the first conductive semiconductor layer 30A, theactive layer 30B, and the second conductive semiconductor layer 30C.Preferably, a thickness of the second conductive semiconductor layer 30Cmay be in a range of 50 nm to 500 nm, but the thickness is not limitedthereto. Since light emission of the nano-scale-LED element is notlimited to the blue color, when a color of the light emission is varied,a different kind of III-V semiconductor material may be used as thep-type semiconductor layer without limitation.

In accordance with one preferred embodiment of the present disclosure,the nano-scale-LED element may further include a first electrode layerformed under the first conductive semiconductor layer and a secondelectrode layer formed over the second conductive semiconductor layer.FIG. 15 illustrates a first electrode layer 30D formed under the firstconductive semiconductor layer 30A, and a second electrode layer 30Eformed over the second conductive semiconductor layer 30C.

When the first electrode layer 30D and/or the second electrode layer 30Eare formed under or over the first or second conductive semiconductorlayer, there is an advantage in that a metal ohmic layer may be formedat a temperature that is lower than that required to form the metalohmic layer at a connection portion between a semiconductor layer and anelectrode line of the nano-scale-LED element.

The first electrode layer 30D and the second electrode layer 30E may beeach configured using a metal or a metal oxide which is generally usedas an electrode of an LED element, and preferably, using chrome (Cr),titanium (Ti), aluminum (Al), gold (Au), nickel (Ni), indium tin oxide(ITO), and an oxide thereof or alloy thereof alone or in combination,but the first electrode layer 30D and the second electrode layer 30E arenot limited thereto. Preferably, a thickness of each of the firstelectrode layer 30D and/or the second electrode layer 30E may be in arange of 1 nm to 100 nm, but the thickness is not limited thereto. Also,the thicknesses and materials of the first electrode layer 30D and/orthe second electrode layer 30E may be different from each other or thesame as each other.

Meanwhile, a nano-scale-LED element included in one preferred embodimentof the present disclosure may include the insulating film 30F providedat an outer surface of the nano-scale-LED element and configured toentirely cover at least an outer surface of an active layer to preventan electrical short circuit that may occur due to a contact betweenouter surfaces of nano-scale-LED elements included in a separation spacebetween two different adjacent electrodes. In addition, the insulatingfilm 30F may preferably coat even on one or more outer surfaces of thefirst conductive semiconductor layer 30A and the second conductivesemiconductor layer 30C to simultaneously prevent an electrical shortcircuit and a degradation of durability of the nano-scale-LED elementdue to damage to the outer surfaces of the semiconductor layers. Theinsulating film 30F may preferably include one or more among siliconnitride (Si₃N₄), silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), hafniumoxide (HfO₂), yttrium oxide (Y₂O₃), and titanium dioxide (TiO₂), andmore preferably, a transparent material made of the above describedingredients, but the insulating film 30F is not limited thereto. Atransparent insulating film may serve as the above described insulatingfilm 30F, and, at the same time, may minimize a decrease of lightemitting efficiency which occurs due to a coating of the insulating film30F.

Meanwhile, the insulating film 30F of the nano-scale-LED elementincluded in one preferred embodiment of the present disclosure may notbe coated on one or more of the first electrode layer 30D and the secondelectrode layer 30E of the nano-scale-LED element, and more preferably,the insulating film 30F may not be coated on both the electrode layers30D and 30E. Although an electrical connection should be establishedbetween the two electrode layers 30D and 30E and adjacent differentelectrodes of an electrode line, when the insulating film 30F is coatedon both the two electrode layers 30D and 30E, the insulating film 30Fmay interfere with the electrical connection so that light emission ofthe nano-scale-LED element may be decreased or the electrical connectionmay not be established such that there is a problem in that the lightemission of the nano-scale-LED element may not occur. However, when anelectrical connection is established between the two electrode layers30D and 30E of the nano-scale-LED element and the adjacent differentelectrodes, there may be no difficulty in light emission of thenano-scale-LED element and the insulating film 30F may be coated onouter surfaces of the two electrode layers 30D and 30E except for endportions of the two electrode layers 30D and 30E of the nano-scale-LEDelement.

Also, a nano-scale-LED element included in one preferred embodiment ofthe present disclosure may further include a hydrophobic film 30G overthe insulating film 30F. The hydrophobic film 30G is provided to enablea surface of the nano-scale-LED element to have a hydrophobiccharacteristic so that an aggregation phenomenon between thenano-scale-LED elements is prevented. When the nano-scale-LED element ismixed in a solvent during the manufacturing process of the electrodeassembly, the hydrophobic film 30G may eliminate a problem of acharacteristic degradation of an independent nano-scale-LED element byminimizing aggregation between the nano-scale-LED elements, and mayenable position alignment to be performed on individual nano-scale-LEDelements in a separation space between two adjacent differentelectrodes.

The hydrophobic film 30G may be formed on the insulating film 30F. Inthis case, a usable hydrophobic film may employ any material that may beformed on an insulating film to prevent an aggregation phenomenonbetween nano-scale-LED elements without limitation, and may preferablybe configured using a self-assembled monolayer (SAM) such asoctadecyltrichlorosilane (OTS), fluoroalkyltrichlorosilane,perfluoroalkyltriethoxysilane, and the like, and a fluoropolymer such asTeflon, Cytop, and the like alone or in combination, but the hydrophobicfilm 30G is not limited thereto.

The above described electrode assembly according to one preferredembodiment of the present disclosure may be manufactured by themanufacturing process which will be described below. However, themanufacturing of the electrode assembly is not limited to themanufacturing process which will be described below.

An electrode assembly according to one preferred embodiment of thepresent disclosure may be manufactured by a manufacturing process whichincludes Operation (1) of forming a first electrode on a base substrate,forming a second electrode on the base substrate to be spaced apart fromthe first electrode, and disposing a first lateral surface of the firstelectrode to face a second lateral surface of the second electrode,Operation (2) of introducing a plurality of nano-scale-LED elements anda solvent to a separation space between the first electrode and thesecond electrode, and Operation (3) of applying electrical power to thefirst electrode and the second electrode to self-align the plurality ofnano-scale-LED elements so that one end of each of the plurality ofnano-scale-LED elements may come into contact with the first lateralsurface of the first electrode and the other end thereof may come intocontact with the second lateral surface of the second electrode.

FIG. 16 is a schematic view illustrating a manufacturing processaccording to one preferred embodiment of the present disclosure. FIG.16A illustrates a first electrode 110 formed on a base substrate 100, asecond electrode 120 formed on the base substrate 100 and disposed toface a first lateral surface of the first electrode 110, and anano-scale-LED element 130 and a solvent 140 introduced to a separationspace between the first electrode 110 and the second electrode 120.Subsequently, as shown in FIG. 16B, when electrical power is applied tothe first electrode 110 and the second electrode 120, the nano-scale-LEDelement 130 is rotated and a position of the nano-scale-LED element 130is changed so that, as shown in FIG. 16C, one end of the nano-scale-LEDelement 130 comes into contact with the first lateral surface of thefirst electrode 110 and the other end thereof comes into contact with asecond lateral surface of the second electrode 120, and a plurality ofnano-scale-LED elements 30 a, 30 b, and 30 c form a multilayer and aredisposed between the first electrode 110 and the second electrode 120.

First, in Operation (1) according to one preferred embodiment of thepresent disclosure, the first electrode is formed on the base substrate,the second electrode is formed on the base substrate to be spaced apartfrom the first electrode, and the first lateral surface of the firstelectrode is disposed to face the second lateral surface of the secondelectrode.

A description of the base substrate, the first electrode and the secondelectrode, and a detailed disposition of the first electrode and thesecond electrode is the same as the descriptions above, and thus it willbe omitted, and a method for manufacturing electrode lines on the basesubstrate will be described below. However, the method for manufacturingelectrode lines is not limited to the method which will be describedbelow.

FIG. 17 is a perspective view illustrating a manufacturing process ofelectrode lines formed on a base substrate according to one preferredembodiment of the present disclosure, and FIG. 17A illustrates a basesubstrate 100 at which electrode lines are formed. Next, as shown inFIG. 17B, a photo resist (PR) 101 may be coated on the base substrate100. The PR may be a PR that is generally used in the related art. Amethod for coating the PR on the base substrate 100 may be one amongspin coating, spray coating, and screen printing, and preferably, may bespin coating, but it is not limited thereto, and a detailed method mayemploy a known method in the related art. A thickness of the PR 101 thatis coated may be in a range of 0.1 μm to 10 μm. However, the thicknessof the PR 101 that is coated may vary according to a thickness of anelectrode that will be deposited on the base substrate.

After the PR 101 is formed on the base substrate 100 as described above,a mask 102 on which patterns 102 a and 102 b, which correspond toelectrode lines with which the first electrode and the second electrodeare to be alternately disposed and spaced apart from each other on thesame plane (See, FIG. 4), are drawn may be placed on the PR 101 as shownin FIG. 17C, and then ultraviolet light may be irradiated toward themask 102.

Thereafter, portions of the PR that are not exposed to the ultravioletlight may be removed by being dipped in a conventional PR solvent, andan exposed portion of the PR at which electrode lines are formed asshown in FIG. 17D may be removed through such an operation. A width ofthe pattern 102 a corresponding to the first electrode of the electrodelines may be in a range of 100 nm to 50 μm, and a width of the pattern102 b corresponding to the second electrode thereof may be in a range of100 nm to 50 μm, but the widths are not limited to the described above.

Afterward, as shown in FIG. 17E, an electrode forming material 103 maybe deposited at a portion at which the PR is removed in the form of theelectrode lines drawn on the mask 102. The electrode forming materialmay be a material of the above described electrode, and a descriptionthereof will be omitted. Materials forming the first electrode and thesecond electrode may be different from each other or the same as eachother. The deposition of the electrode forming material may be performedby one among thermal deposition, e-beam deposition, sputteringdeposition, and screen printing, and preferably, may be thermaldeposition, but the deposition is not limited thereto.

After the electrode forming material 103 is deposited as shown in FIG.17F, the PR 101 coated on the base substrate 100 may be removed usingone PR remover among acetone, N-methylpyrrolidone(1-methyl-2-pyrrolidone (NMP)), and dimethyl sulfoxide (DMSO) so thatelectrode lines 103 a (10 in FIG. 3) and 103 b (20 in FIG. 3) depositedon the base substrate 100 may be manufactured.

In the electrode lines including the first electrode and the secondelectrode which are manufactured through the above described methodaccording to one preferred embodiment of the present disclosure, a unitelectrode area, that is, an area of a region at which the nano-scale-LEDelements and two electrodes capable of independently driving thenano-scale-LED elements are disposed, may preferably be in a range of 1μm² to 100 cm², and more preferably, may be in a range of 10 μm² to 100mm², but the unit electrode area is not limited to the above describedarea. Also, a single unit electrode or a plurality of unit electrodesmay be included in the electrode lines.

Next, in Operation (2) according to one preferred embodiment of thepresent disclosure, the plurality of nano-scale-LED elements and thesolvent are introduced to the separation space between the firstelectrode and the second electrode.

Operation (2) according to one preferred embodiment of the presentdisclosure is an operation of introducing the plurality ofnano-scale-LED elements and the solvent to the separation space betweenthe first electrode and the second electrode of the electrode lineswhich are manufactured as described above. The plurality ofnano-scale-LED elements and the solvent may be introduced to theelectrode lines in a solution state in which the plurality ofnano-scale-LED elements are mixed in the solvent before being introducedto the electrode lines, or the plurality of nano-scale-LED elements maybe introduced between two different adjacent electrodes and then thesolvent may be introduced to the electrode lines. When the plurality ofnano-scale-LED elements and the solvent are introduced in the solutionstate, a solution may be in an ink phase or a paste phase.

A detailed description regarding the nano-scale-LED element is the sameas the description above, and thus it will be omitted.

The solvent may preferably be a solvent selected from a group consistingof acetone, water, alcohol, and toluene, and more preferably, may beacetone. However, a kind of solvent is not limited to the describedabove, and any solvent which is easily evaporated without physically orchemically affecting the nano-scale-LED element may be used withoutlimitation.

Preferably, 0.001 to 100 parts by weight of the nano-scale-LED elementmay be introduced on the basis of 100 parts by weight of the solvent.When less than 0.001 parts by weight of the nano-scale-LED element isintroduced, the number of nano-scale-LED elements connected to the twoelectrodes may be reduced so that it may be difficult for the electrodeassembly including the nano-scale-LED elements to normally function, andthere may be a problem in that the solution should be added severaltimes to address such a difficulty. When more than 100 parts by weightof the nano-scale-LED element is introduced, there may be a problem inthat an alignment of each of the nano-scale-LED elements may beinterfered with.

In the present disclosure, the method for introducing the nano-scale-LEDelements and the solvent to the separation space between the firstelectrode and the second electrode is not specifically limited. As anon-limiting example, when the nano-scale-LED elements and the solventare introduced in the solution state, the solution may be dropped overthe first electrode and the second electrode to flow into the separationspace between the first electrode and the second electrode adjacentthereto. To facilitate an insertion of a nano-scale-LED element into theseparation space between two different adjacent electrodes to beconnected to the two different adjacent electrodes, the nano-scale-LEDelement may preferably be pre-located in the separation space beforeOperation (2), which will be described below, is performed.

To this end, in accordance with one preferred embodiment of the presentdisclosure, the first electrode and the second electrode may include aportion in which a width of each of the first and second electrodesnarrows toward the upward direction that is perpendicular to the basesubstrate. With such a configuration, a solution introduced from theelectrode lines may flow into the separation space between the first andsecond electrodes without remaining on an upper surface of each of thefirst and second electrodes.

FIG. 18 is a schematic view of Operation (2) according to one preferredembodiment of the present disclosure, and illustrates first electrodes111 and 112 formed on a base substrate 100, a second electrode 121formed to have lateral surfaces disposed to face the first electrodes111 and 112, a plurality of nano-scale-LED elements 131 and 132, and asolvent 140. In the case in which an upper surface of each of theelectrodes is parallel to the base substrate, when the nano-scale-LEDelements or a solution including the nano-scale-LED elements falls ontothe electrodes, some of the nano-scale-LED elements 131 may be locatedat the upper surface of the first electrode 111. On the other hand, across section of an electrode includes a portion in which a widththereof narrows toward the upward direction that is perpendicular to thebase substrate, and, for example, the electrodes 121 and 112 each havingan electrode width w₂ of an upper end part that is narrower than anelectrode width w₁ of a lower end part may have an advantage in that,when the nano-scale-LED elements or the solution including thenano-scale-LED elements falls onto the electrodes, the nano-scale-LEDelements may flow down along inclined surfaces of the electrode as inRoute Z in FIG. 18 and may be located in a separation space between theelectrodes, which is a destination of the nano-scale-LED elements.

Next, in Operation (3) according to one preferred embodiment of thepresent disclosure, electrical power is applied to the first electrodeand the second electrode to self-align the plurality of nano-scale-LEDelements so that one end of each of the plurality of nano-scale-LEDelements may come into contact with a first lateral surface of the firstelectrode and the other end thereof may come into contact with a secondlateral surface of the second electrode.

Charges are induced in the nano-scale-LED elements by an induction of anelectric field that is formed by a potential difference between the twoelectrodes, and both ends of each of the nano-scale-LED elements havedifferent charges in a length direction centering on the center of eachof the nano-scale-LED elements. Therefore, the one end of each of thenano-scale-LED elements, which is charged with a positive charge, comesinto contact with a lateral surface of the second electrode which has acharge opposite thereto, and the other end thereof, which is chargedwith a negative charge, comes into contact with a lateral surface of theother electrode which has a charge opposite thereto so that thenano-scale-LED elements may be self-aligned to be interposed in theseparation space. In the case in which LED elements each have a sizethat may be visually recognized and may be picked up using aninstrument, the LED elements may be directly physically disposed andinserted into a separation space between different electrodes that areformed to be spaced apart from each other on the same plane to beconnected to the different electrodes. However, it may be difficult todirectly physically dispose the nano-scale-LED elements of the presentdisclosure so that there is a problem in that the nano-scale-LEDelements may not be simultaneously inserted into a separation spacebetween different nano-scale electrodes that are spaced apart from eachother on the same plane to be connected to the different nano-scaleelectrodes. Accordingly, the present disclosure may address the abovedescribed problem by applying electrical power to the electrode lines toenable the nano-scale-LED elements themselves to be simultaneouslyinserted into the separation space between two different electrodes andto be connected to the two different electrodes.

The electrical power may preferably be an alternating current, and morepreferably, a voltage of the electrical power may be in a range of 40 to100 Vpp and the electrical power may be applied for 10 to 120 seconds.When the voltage is less than 20 volts (V) and/or the electrical poweris applied for less than for 10 seconds, an electric filed is notsufficiently formed to self-align nano-scale-LED elements so that thenano-scale-LED elements may not be aligned to positions in a separationspace between electrodes as intended. When the voltage exceeds 50 Vand/or the electrical power is applied for more than 120 seconds,excessive electrical power is applied to the nano-scale-LED elementsand/or the electrodes so that the nano-scale-LED elements and/or theelectrodes are damaged and thus there may be a problem in that lightemitting efficiency is degraded or light emission does not occur.

Meanwhile, in Operation (2) according to one preferred embodiment, evenwhen electrical power is applied to the electrode lines according to anaspect ratio of each nano-scale-LED element, it may be difficult toself-align the nano-scale-LED elements. Therefore, in accordance withone preferred embodiment of the present disclosure, the aspect ratio ofeach the nano-scale-LED elements included in the present disclosure maybe in a range of 1.2 to 100, and preferably, may be in a range of 1.2 to50, and more preferably, may be in a range of 1.5 to 20, andparticularly preferably, may be in a range of 1.5 to 10. When the aspectratio of each the nano-scale-LED elements is less than 1.2, there is aproblem in that the nano-scale-LED elements may not be self-aligned eventhough electrical power is applied to the electrode lines. When theaspect ratio exceeds 100, a voltage of electrical power required toself-align the nano-scale-LED elements may be lowered, but it may bedifficult to manufacture the nano-scale-LED elements each exceeding theaspect ratio of 100 due to a limitation in a process of manufacturing anano-scale-LED element using dry etching and the like.

Also, in accordance with one preferred embodiment of the presentdisclosure, both ends of a nano-scale-LED element may each include aconvex curved surface to facilitate a self-alignment of thenano-scale-LED element and to reduce a volume occupied by a singlenano-scale-LED element in a separation space so that many nano-scale-LEDelements may be included in the separated space. FIG. 19 is a plan viewillustrating a self-alignment of a nano-scale-LED element according toone preferred embodiment of the present disclosure. When electricalpower is applied to a first electrode 113 and a second electrode 123which are formed on a base substrate 100 and are spaced apart from eachother, both ends of a nano-scale-LED element 133 are rotated by a indifferent electrode directions. As shown in FIG. 19, in the case inwhich both of the ends of the nano-scale-LED element 133 do not includea curved surface, a self-aligned nano-scale-LED element 133′ may beinserted between the two different electrodes 113 and 123 to beconnected to the two different electrodes 113 and 123, but there is aproblem in that the self-aligned nano-scale-LED element 133′ may not beconnected perpendicular to lateral surfaces of the two differentelectrodes 113 and 123 in a length direction of the self-alignednano-scale-LED element 133′. FIG. 20 is a plan view illustrating aself-alignment of a nano-scale-LED element according to one preferredembodiment of the present disclosure. When electrical power is appliedto a first electrode 114 and a second electrode 124 which are formed ona base substrate 100 and are spaced apart from each other, both ends ofa nano-scale-LED element 134 are rotated by β in different electrodedirections. At this point, in the case in which both of the ends of thenano-scale-LED element 134 include a curved surface as shown in FIG. 20,there is an advantage in that the nano-scale-LED element 134 may be moreeasily positionally aligned to be perpendicular to lateral surfaces oftwo different electrodes in a length direction of the nano-scale-LEDelement 134 when compared to the nano-scale LED element 133 in FIG. 19.

Although the technical spirit of the present disclosure has beenspecifically described according to the above-described preferredembodiments, it should be noted that the above described embodiments areintended only for describing the present disclosure and not to limitthereto. In addition, it should be understood that various embodimentscan be devised by those skilled in the art within the scope and thetechnical spirit of the present disclosure.

The invention claimed is:
 1. An electrode assembly comprising: a basesubstrate; a first electrode located on the base substrate; a secondelectrode located on the base substrate to face the first electrode; anda plurality of light emitting diode (LED) elements interposed betweenthe first electrode and the second electrode, wherein at least one endof each of the plurality of LED elements is in contact with the firstelectrode or the second electrode, and at least a portion of the firstelectrode and at least a portion of the second electrode is disposed onthe base substrate, and each of the first electrode and the secondelectrode comprises a first surface which is a contact surface betweenthe first electrode or the second electrode and the base substrate, anda second surface which faces the at least one end of the plurality ofLED elements, wherein the first surface of the first electrode and thesecond electrode that are in direct contact with the base substrate isnot parallel with the second surface, and wherein a lower lateralsurface in cross-section of an entire lateral surface of an LED elementof the plurality of LED elements does not contact the first electrodeand the second electrode directly, and wherein the plurality of LEDelements comprises a first LED element and a second LED element, whereina first distance between a farthest point and a closest point from thebase substrate of the first LED element is different from a seconddistance between a farthest point and a closest point from the basesubstrate of the second LED element.
 2. The electrode assembly of claim1, wherein the contact surface between the at least one end of each ofthe plurality of LED elements and the first electrode or the secondelectrode is perpendicular to the base substrate.
 3. The electrodeassembly of claim 1, wherein the plurality of LED elements forms amultilayer based on the base substrate.
 4. The electrode assembly ofclaim 1, wherein each of the plurality of LED elements includes: a firstconductive semiconductor layer; an active layer formed on the firstconductive semiconductor layer; a second conductive semiconductor layerformed on the active layer; and an insulating film configured toentirely cover at least an outer surface of the active layer among outersurfaces of each of the plurality of LED elements.
 5. The electrodeassembly of claim 4, wherein the first conductive semiconductor layer,the active layer, and the second conductive semiconductor layer aresequentially formed to be parallel with the base substrate.
 6. Theelectrode assembly of claim 1, wherein the second surface of the firstelectrode is perpendicular to the base substrate; wherein the secondsurface of the second electrode faces the second surface of the firstelectrode and is perpendicular to the base substrate; and wherein theplurality of LED elements having one end thereof which comes intocontact with the second surface of the first electrode and other endthereof which comes into contact with the second surface of the secondelectrode.
 7. The electrode assembly of claim 6, wherein the secondsurface of the first electrode and the second surface of the secondelectrode are parallel to each other.
 8. The electrode assembly of claim6, wherein a height of the second surface of each of the first electrodeand the second electrode ranges from 1.1 to 10 times a diameter of eachof the plurality of LED elements.
 9. The electrode assembly of claim 2,wherein the plurality of LED elements are connected to the firstelectrode and the second electrode to be perpendicular thereto in adirection of long axis of each of the plurality of LED elements.
 10. Theelectrode assembly of claim 1, wherein both ends of each of theplurality of LED elements include a convex curved surface.
 11. Theelectrode assembly of claim 1, wherein each of the first electrode andthe second electrode includes a portion in which a width of each of thefirst electrode and the second electrode narrows toward an upwarddirection that is perpendicular to the base substrate.
 12. An electrodeassembly comprising: a plurality of LED elements in a separation spacebetween a first electrode and a second electrode, and configured toenable one end of each of the plurality of LED elements to come intocontact with the first electrode and other end thereof to come intocontact with the second electrode, wherein at least one end of theplurality of LED elements is in contact with the first electrode or thesecond electrode, and at least a portion of the first electrode and atleast a portion of the second electrode is disposed on a base substrate,and each of the first electrode and the second electrode comprises afirst surface which is a contact surface between the first electrode orthe second electrode and the base substrate, and a second surface whichfaces the at least one end of the plurality of LED elements, wherein thefirst surface of the first electrode and the second electrode that arein direct contact with the base substrate is not parallel with thesecond surface, wherein a lower lateral surface in cross-section of anentire lateral surface of an LED element of the plurality of LEDelements does not contact the first electrode and the second electrodedirectly, wherein 1×10³ to 1×10¹²/mm³ of the plurality of LED elementsare included in the electrode assembly, and wherein the plurality of LEDelements comprises a first LED element and a second LED element, whereina first distance between a farthest point and a closest point from thebase substrate of the first LED element is different from a seconddistance between a farthest point and a closest point from the basesubstrate of the second LED element.
 13. A method for manufacturing anelectrode assembly, comprising: (1) forming a first electrode on a basesubstrate, forming a second electrode on the base substrate to be spacedfrom the first electrode, wherein the first electrode is configured toface the second electrode; (2) introducing a plurality of LED elementsand a solvent to a separation space between the first electrode and thesecond electrode; and (3) applying electrical power to the firstelectrode and the second electrode so that one end of each of theplurality of LED elements comes into contact with the first electrodeand other end thereof comes into contact with the second electrode, andat least a portion of the first electrode and at least a portion of thesecond electrode is disposed on the base substrate, and each of thefirst electrode and the second electrode comprises a first surface whichis a contact surface between the first electrode or the second electrodeand the base substrate, and a second surface which faces at least oneend of the plurality of LED elements, wherein the first surface of thefirst electrode and the second electrode that are in direct contact withthe base substrate is not parallel with the second surface, and whereina lower lateral surface in cross-section of an entire lateral surface ofan LED element of the plurality of LED elements does not contact thefirst electrode and the second electrode directly, wherein the pluralityof LED elements comprises a first LED element and a second LED element,wherein a first distance between a farthest point and a closest pointfrom the base substrate of the first LED element is different from asecond distance between a farthest point and a closest point from thebase substrate of the second LED element.
 14. The method of claim 13,wherein a voltage of the electrical power applied to the first electrodeand the second electrode for 10 to 120 seconds is in a range of 10 to500 Vpp.